The present invention relates generally to tape drives, and more particularly to an apparatus which positions a magnetic read/write head relative to a length of magnetic tape. The disclosure of commonly assigned U.S. Patent Application Ser. No. 849,410, filed Apr. 7, 1986 and entitled "Cartridge Loading Apparatus", is hereby incorporated by reference.
Many small business and personal computer systems utilize backup memory devices in the event of a malfunction in the principal memory device of the computer. Previously, floppy disk drive units have been used to store data in such an event. As an alternative to floppy disk drives, streaming tape drives have been developed as a means for storing data on a length of 1/4" wide magnetic tape which is wound within a tape cartridge. As a backup memory device, tape drives are preferably to floppy disk drives because tape drives have a much greater storage capacity, and can load data onto a computer much more quickly.
To store as much data as possible on the magnetic tape, the data is recorded on a number of parallel, longitudinally oriented tracks on the tape. In order to read and write the data onto the tape in separate tracks, the magnetic head must be able to move transversely across the tape in increments as small as the width of a track, and be maintained in the proper orientation at each track. Typically, a lead screw driven by a stepper motor is provided for this purpose. The head is mounted on a positioning apparatus which threads onto the lead screw so that for a given amount of rotation of the lead screw, the head is displaced a predetermined distance across the tape.
To increase the data storage capacity of the tape, the tape is divided into more tracks which are smaller in width. As a result, the head must be positioned with even greater precision. Thus, the clearance between the head positioning apparatus and the lead screw must be minimized to prevent motion of the head other than when the lead screw is rotating.
Further, it is desirable for the head positioning apparatus to occupy as little space as possible. This enables the external dimensions of the tape drive to be minimized, so that the tape drive can fit within a standard size enclosure within a computer.
Thus, a need exists for a compact head positioning apparatus which allows precise positioning of a magnetic head so that multiple tracks of data may be recorded on a length of magnetic tape.